ya i work at a caterpillar dealership. Cat hasn't made over the road truck engines since 2007 i believe because they can't meet emissions. but you can buy a 2010 kenworth truck with a 2007 cat motor. as long as the motor was made when it was still legal it is fine.
No, Cat still made truck application engines through early to mid 2009, the "2007" moniker refers to the emissions rule. Since Cat's announcement in late 2008 that they were exiting the heavy truck engine market, they pretty well lost all remaining popularity except for the die-hard fans. Where before dealers couldn't keep a new Cat powered truck on the sales lot, now they have steep discounts over Cummins just to get them off the lot. Cat's ACERT technology didn't live up to what it was supposed to, resulting in significant warranty and reliability problems. Cat made a strategic decision to quit chasing emissions regs as the 3 year window for each new reg tightening didn't provide a chance to recoup the cost of the engineering investment, especially with the almost non-existent new truck market since 2007.
The big three emissions benchmarks are 10/02 for Oct '02, 2007 and 2010. You will note that most light duty diesels and the trucks they go in also had major changes around each of those times to accomodate the changes. 10/02 brought in EGR technology, 2007 brought in DPF's and 2010, for the most part, brings in urea injection. Incidentally, 10/02 was really the 2004 emission regulation that was pushed up 15 months as the result of a settlement between the EPA and engine manufacturers after they were caught cheating on emissions testing and certifications. They chose to implement the '04 regs 15 months early as part of the settlement. As a result, 15 months was shaved off of test and evaluation time, leading to the relative catastrophe with the early 10/02 emissions trucks, especially Cat and Mack diesel engines.
As said in earlier posts, the emissions rules apply to engine build dates, not chassis build dates. Auto makers really cheat on the "model year" designation, sometimes building/selling them as early as the prior January (some '07 GM NBS SUV's were built in November '05). I believe most change over generally around mid June to mid July. I know my '08 Sierra was built Aug 7th 2007.